As much as I really enjoy 3D printing, and also the ability to make almost anything, I’d first check online for a replacement pump. Sears Parts will have the diagrams and part numbers for almost any make and model dishwasher. Once you’ve found the part number, do a Google search for it and you’ll find a wide range of places that will sell the pump including Amazon and Ebay (if you’re in North America). The cost is likely to be pretty low compared to the time and effort to design and print your own new wheel, plus you see the comments below about material selection. A new printed wheel isn’t going to have even a fraction of the lifespan of a new injection molded one. Depending on the make/model, you may end up replacing the entire pump, not just the wheel, but that will also serve to extend the life.
I say this as an avid DIY who rarely calls a service. I think my last one was for a blown AC compressor as I can’t justify the cost of the tools for refrigerant recovery. I do have a vacuum pump though
