A pool pump can be an expensive investment, depending on the size of the pool. If you get a hairline crack in the pump's housing, it could leak water. Replacing a pump is an option but you could try to avoid spending the money for a new pump and seal the pump's crack with epoxy resin. Sealing the crack could give you many additional years of usage.
Turn the pump off and allow the water to drain out of the housing. Wait until no more water seeps from the crack.
Sand the surface area around the crack with 600-grit sandpaper to provide a textured surface for proper epoxy adhesion. Sand at the surface at least ½-inch around the circumference of the crack.
Wipe the surface clean with mineral spirits and a clean rag.
Mix your two-part epoxy in a small container and then apply the epoxy over the cracked surface that you sanded. Allow 24 hours drying time before you restore power to the pump