A structural improvement of the canned pump is to improve the stiffness of a stationary shaft and, according to requirement, to dispose a monitor device. The method for improving the stiffness of the stationary shaft includes axially inserting a shaft metal rear support of the metal structural of a motor rear casing of a canned motor into the inner side of a rotor yoke of an inner rotor of the canned motor, tightly attaching the shaft metal rear support to a rear shaft seat for improving the stiffness of the stationary shaft by longer hold length, and for shortening an arm length of the composite force. The monitor device, used for detecting the wear of a bearing for enhancing the reliability and satisfying the driving requirement, is installed in the ring slot to be protected by the rear shaft seat.