2003 Suzuki Vitara There Leak Rear Left Wheel Took Apart Friend Tells That

There is a leak in the rear left wheel. When we took it apart my friend tells me that the leak is a result of a crack in what I can only describe as a square piece before the wheel bearing. I went to get it pressed out and to replace the square piece only to findout that no one but a dealer carries it. The auto parts store stated that I needed a new bearing as well. I am not sure if the leak has to do with the crackin the square piece I desribed or it is really the inner or outer seal that needs to be replaced. Thank youfor your help