I must agree with the others the water pump is not needed until its failing or you get one at a super deal and are going to do it at the timing belt and accessory replacement stage. The Suby water pumps are long term parts from what I have seen, well over 100k unless they just up and fail. You could put in a new pump in and it could fail the next week, but its super rare for the pump to go.
Also if your mechaninc is doing all the timing stuff now dont replace the stuff at 105k do it at 150+k