They are expensive, but the big one on the passenger side is the easiest and is about $55 or so... If you have time and patience, all the others are round types and usually they sell the inserts for $17 each, I believe... Forget about the one in the back of the tranny, that's a PITA and you're better off waiting until you need to change the tranny, LOL... It may be worth having a machine shop press them in too; I usually change the whole motor with the bracket (which, of course, is more expensive by far) because I changed one of those inserts once, and it was hell getting it outta there(AND in there)... Granted, I was working on the ground using tools out of a bucket, so I didn't use a press, or any air tools, so if you plan it out, it could be much cheaper and easier to replace them than I am saying...
Truthfully, you CAN hurt the axles and whatnot, but if you're not going to keep the car long or suspect something else more expensive is gonna go soon, they leave them be or just change the easiest one... I mean, you have already changed the water pump, so if it feels alright, then let go... If you have a lot of vibrations at idle in drive, then you may want to change at least the one big one on the passenger side...
For the record, just go to autozone and have them pull the motor mount in question, and see how it looks in comparison to yours... Also, on those round mounts, I have stuffed cut pieces of heater hose to kinda give them more life... I'm not rich by any means, so although I speak of what is the "right thing to do", I don't change every part for a new part myself... I just can't complain if I have to suffer the consequence... I fix everything from the engine to tranny to everything else myself, so no matter what, if I abuse a vehicle, it still costs me whatever the parts cost... When you have to pay someone else to fix your car, then you're better off taking precautionary measures...
Hope that helps
Mike