The contribution addresses the problem of robust trajectory tracking control and disturbance rejection for a non contact, high-precision Lorentz force planar motion stage of linear DC brushless type. The control problem is accomplished by using a composite control law including a simple computed torque type controller together with an extended Luenberger type of state and disturbance observer also known as extended state or generalized proportional integral observer (GESO/GPIO). We provide stability proofs and estimation error bounds of the GESO/GPIO related to the choice of the eigenvalues of the observer estimation error dynamics. Finally, we assess the performance of the proposed controller on the basis of a recently developed motion stage model that comprises a realistic disturbance modeling and thus is capable of reflecting the major challenges for control.