While boys are more physical I don't think it is okay for a 10 mos old or 19 mos old to wrestle. They have no comprehension where that level of cut off is. I am just now allowing my son to wrestle around with me or his sister and he is four. I know he needs that physical type contact and it is fun but I waited to give the green light until he was verbal and could comprehend when to stop.
I think allowing it sends mixed signals to them at that age.
I would seperate them the second it starts, period. Say nicely "we be nice to our friends" and seperate them, one in a play pen, another in high chair, whatever for a few minutes. Then get out a new toy and get them interacting together again. If is starts up, remove them and reprimand them. You need to have the 19 mos old's mom on board too, if he is allowed to be rough and tumble at home he will not know when it is okay and not okay and could easily hurt your son or vice versa.
I watch boys, ages 3 1/2 to 9, I do not allow wrestling, running or rough play in my house at all. I let them burn off steam outside in the yard or at the playground but it is not allowed in my home. I am responsible for them as you are that 19 mos old and it is something too easy to get out of hand. Just set clear boundaries and seperate them the second it starts, do not wait until someone gets hurt.
When your son is older, then you can discuss with him what is fun play and what is too rough, right now they will not get it!