(This is advice for games that are played in person or in a largely synchronous setting like a chat. If you're playing by forum a lot of it won't work well just from your end, and you'll need to establish an alternate gameflow by sharing your players' concerns with each other up front.)
The hot-headed fight-happy freebooter who has to be restrained by the better angels among their companions is a reasonable character to want to play, and you can make it work, but not accidentally. It's possible for characters in Dungeon World to meaningfully clash with each other without running into the issues that might arise in a game with a more rigid action structure.
I'll say this up front: it's only going to work if both sides are okay with letting the dice settle this, and that means being okay with every possible outcome, as long as they get their chance. If Leafwillow and Sir Justice's players are cool with trying and failing to hold Grognak back sometimes, and Grognak's player is cool with trying and failing to get out from under Leafwillow (who is currently a hippopotamus with a wooden leg) sometimes, then everything's cool.
So here's how to make that happen. Well, first:
0) Nothing Happens Unless You Let It
Dungeon World is a conversation. When you're having a conversation about where to get dinner and somebody shouts "Jack in the Box!" you don't all just immediately go to Jack in the Box because it's the first thing somebody said, do you? You let everyone talk about where they want to go and make a decision together after hearing what everybody has to say.
In much the same way, when you're describing a tavern scene and mention a cloaked figure, and Grognak's player screams "GROGNAK SMASH!" and pitches some dice, that doesn't actually mean that Leafwillow and Sir Justice have to stand there poleaxed while Grognak smashes through three poker games and a marriage proposal to get at the cloaked figure. You're the GM. You control the universe. Nothing is going to happen until you say it does, and that means that you can take Grognak's input without saying what comes of it, and then turn to Leafwillow and Sir Justice and let them have their say.
Okay, they've all had a chance to tell you what they're doing in this open-ended scene. Now what?
1) How To Stop A Fight
Dungeon World has no concept of initiative order or equal goes. People take actions and get the opportunity to take actions as it is dramatically appropriate.
So, when Sir Justice stands in defense of the tavern patrons and rolls Defend, and when Leafwillow frantically grabs at Grognak to hold him back and rolls Interfere, this doesn't "use up their actions". It's not "Grognak's turn" again. You get to decide how the tavern reacts and who gets the spotlight as a result of it. "I'm going to let go" could turn out to be excellent leverage for Leafwillow to Parley with the cloaked figure, for example.
This second bit is the more usual flow of running Dungeon World, by the way. Everyone entangled in a dramatic situation, and you pick one person at a time to talk to and make some progress on their corner of it. For those times when you're just describing the world and not necessarily looking at anyone for an answer, you're not obligated to humor the first person to speak up - you weren't talking to anybody, so you can wait to hear from everybody.
2) A Little More Conversation
But you also mentioned wanting their characters to talk to each other more, which is also cool. So here are some ideas for letting that come out.
- You can put a decent amount of "dead time" in Dungeon World, after you stop running down the collapsing building of the first session. There are Perilous Journeys to Undertake that last days at a time, Making Camp means there's a watch to set as people settle in for the night, and sometimes you need to wait until it's dark out, or bright out, or the dragon gets bored with inspecting every hidey-hole in the mountainside and flies away. In those times you can prompt for some reflection and conversation. Not, like, full-on community theater conversation, if that ain't everyone's jam. What do you talk about? Well:
- Everyone's written bonds with each other, right? Grognak's put Leafwillow and/or Sir Justice in some of his bonds, Leafwillow and Sir Justice have put Grognak in some of theirs, and everyone's been okay with where they wound up? Everyone has to be okay, by the way. That's a rule. You can't write down a bond that one side isn't good with being a part of. They might not agree with what the bond says, but that's just what the character holding the bond thinks. Ask both people involved in the bond how they think it might resolve. Maybe a conversation's a good way to make that happen.
- Heck, nothing says Leafwillow has to actually try and grapple with Grognak to roll Interfere. A stern talking-to can be just as distracting.
If people are okay with playing off each other dramatically, okay with not succeeding at their violence/nonviolence as long as they've had their go, then having some of your adventuring group butt heads now and again can make for some really satisfying drama. Just be ready and willing for either side to come out on top.