water pump question

i was wondering if there was a way you could test to see if your water pump was working good or not, its on an sr20.

my car has been running hot lately and i have an aftermarket temp guage and it jumps around alot, it will heat up then cool down then heat up again. it never stays constant, i wanted to see if it might be my water pump...

well if you never replaced the water pump, it would better if you did, but i dont know of way.