A sensor assembly for measuring movements of a fluid pump driven by an electric motor, the electric motor connectable to a feed voltage, the sensor assembly comprising an accelerometer electrically connected to a bias circuit, the latter comprising a feed terminal electrically connectable to the feed voltage of the motor and a signal terminal electrically connectable to an external measuring terminal. A fluid pump is also described, comprising a cylinder, a piston, a housing comprising a hermetic terminal and hermetically enclosing the cylinder and the piston, thus forming a hermetic assembly, the piston driven by an electric motor, the electric motor connected to an electric voltage by a pair of voltage terminals associated to the hermetic terminal, the fluid pump comprising a sensor assembly associated to the cylinder comprising a feed terminal connected to one of the voltage terminals and a signal terminal electrically connected to an external measuring circuit.