An embodiment of the present disclosure discloses a motor assembly including a rotation shaft, an impeller including a hub fastened to the rotation shaft, and a plurality of blades protruding outward from an outer surface of the hub, an inlet body for surrounding an outer circumference of the impeller, and a coating layer coated on an inner surface of the inlet body, wherein at least a portion of the coating layer is ground in a form of powder by friction with the plurality of blades during rotation of the impeller.