To get out the calcium deposits vineger works well. Some people dilute it, but I use it straight. Fill up the volute and let it sit over night. The mag you can just drop it in a bowl or bucket of vineger. After that rinse it out with warm water. If that does not work you can dissasimble the pump and soak the components. Be careful during assembly and disassembly to not damage the components some, esp the mag, can break easily.
If you are lazy, and can get cheap vinegar (buy it by the gallons from Costco!), go ahead. It is still wasteful, BTW.
I like to able to visually see the clean part, so I just disassemble and reassemble the pump after soaking them in vinegar.
I usually heat the vinegar in microwave to near boiling before dumping the parts in. Diluted vinegar still work better than "neat" cold vinegar if you heat the solution up. Watch that fuzz!