Sump pumps need to be regularly maintained as even the best quality pumps deteriorate over time with the average sump pump's lifespan only being about 5-7 years. To extend the life of your pump, you should clean it out every year and after each heavy rainfall. Check the motor and the float that they are moving normally and verify the oil seal. Every few months, do a quick visual check to make sure that everything looks right with your pump.
Plumbing pumps including sump pumps can be found at www.supplyhouse.com