I don't blame Bono for being upset. It probably really hurts when he's playing like that!
When you say they don't get along, what exactly is he doing? If you could even video tape them interacting and put it on youtube that would help a lot in figuring out what's going on.
Bono may just be correcting Volka, as Volka is still a puppy and doesn't have very good dog manners right now. If that's the case, it's actually a good thing because that's how dogs learn to interact with other dogs. They usually learn from their moms and siblings when they're a lot younger, but he would have learned that it's okay to be more physical with them because they're his size.
What kind of training and socialization is Volka getting? Does he get to play with dogs other than Bono?
I wouldn't let them together unsupervised at this point. Without seeing their interaction in person, my recommendation is to put Volka on a leash and have him drag it around the house (supervised) so that you can rescue Bono if Volka is in his face too much. Let him approach Bono, and reward him when he's gentle/not physical. Teach him to lay down when Bono is near him. When he is laying down it will be harder for him to be so physical and Bono might not feel as threatened.
My hunch is that once Volka learns to play more gently Bono will become more tolerant of him. After that they may even become friends.