Check for seepage from the weep hole, and listen for any noise of the bearing. If the impeller is plastic, it can become brittle with age and break vanes, which leads to overheating under stressed conditions. If the timing belt or other work is done on the front side of the engine and the water pump has a lot of miles on it, it is sometimes more cost effective to consider pre-emptive replacement.
If all is well, without seepage noise or over-heating, then leave it alone and just change the coolant as specified.