An insert (70) for a clamping element with two jaws to clamp a rod-shaped element comprises an inner cavity (144) to accommodate a rod-shaped element and at least one flange element (153) at one longitudinal end of the insert intended to abut against the clamping element. The flange element (153) comprises clamping members (161) to reduce the available room within the inner cavity (144) for the rod-shaped element to be clamped and to clamp the flange element (153) between the rod-shaped element and an outer clamping surface of the clamping element to prohibit any longitudinal movement of the clamped insert.