We had a similar problem, the pump just quit working but we didn't blow any fuses. It turned out to be a bad internal ground inside the motor, a fairly common problem.
If you remove the hot wire to the pump and activate the switch, does it still blow the fuse? If it still blows, then the problem is somewhere between the control panel and the motor.
Let us know what you find.
Denny, Connie & Shadow (former barn cat made good)
2000 Itasca Horizon, Cat 3126B, Freightliner Chassis