The pump is a gear pump with internal gear. The innovation of the pump is a variable adjustment of the work space. The change of the work space is obtained by movement (along the pump axis) of the limiting insert mounted on the drive wheel rotor. The insert is connected by means of a spring with an adjustment screw. Tightening the screw reduces the work space, unscrewing increases the work space. This allows to control the pump’s performance. The screw adjusting the work space can be retrofitted with an electronic system. In addition, the pump is equipped with flood channels connected to the work space supplied via the input, so that it does not run dry when it is started up. In addition, the pump has levelling channels.