If you see ANY fluid leaking from the little sipe hole, in the casting of the pump....you are living on borrowed time. That usually means that the bearings are turning in antifreeze. If the sled has lots of miles, I would rebuild it before you have trouble. When they break, it is too late. If you break the drive gear and impeller shaft, you are looking at a new pump because those parts alone are worth almost as much as a complete new one. A complete new pump is around $400-$500 Cnd. Polaris bearings are about $43 dollars each and the mechanical seal is another $45.
I have 3200 miles on my XCR 800 and depending on how many miles I put on my sled this year, I will be rebuilding the water pump next season regardless.