Does the pump need to be covered?

Yes all pumps should be protected from the elements, it is important to protect the motor from water entering it. Most pump manufactures do cover warranty for water entering the motor or electrics. Pumps should not only be covered adequately but they should be positioned so that ground water pooling does not enter the pump housing as well. A pump cover will only extend the life of you pump, be sure the cover has adequate ventilation vent installed.