A motor assembly for use in a downhole submersible pumping system includes an electric motor and a motor protection bag. The motor protection bag surrounds a portion of the exterior surface of the motor to form an impermeable, corrosion-resistant barrier. The motor protection bag comprises a seamless, elongate cylindrical having a substantially constant inner diameter and open ends. The motor protection bag may be constructed from a suitable polymer, such as perfluoroalkoxy (PFA) fluoropolymer. The motor protection bag is held in place along the exterior surface of the motor with a plurality of clamps that prohibit the migration of fluid between the exterior of the motor and the motor protection bag.