These are cheesy, inexpensive dishwashers that are prone to leaky pumps, as shown here (click the pic for the larger, annotated view).
The problem is usually a leaky shaft seal kit, shown here as Items 7 and 8 (click the pic for the larger, annotated view).
Fortunately, the shaft seal kit is inexpensive; but it can be a booger to install, depending on how much rust you’re dealing with. May require a destructive removal of the impeller, too, but ain’t no thang ‘cuz the shaft seal kit comes with a new impeller. Here’s a nice, purdy picture of a brand new shaft seal kit. And just to help motivate you a little more, the money you save from replacing just the shaft seal vs. replacing the entire motor-pump assembly is well over a Benjamin. So you go ahead and drill, cut, and chisel all you want on that old impeller!
And Whirlpool just came out with a spiffy new DIY repair manual for this dishwasher, which will assist you mightily in the many repair adventures you are certain to have with this dishwasher:
To learn more about your dishwasher, or to order parts, click here.