A permanent magnet module to be installed in a rotor includes at least two permanent magnets with the first magnetic pole on the first plane surface and the second magnetic pole on the second plane surface, and a cover at least partially enveloping the permanent magnets. The cover of the module is magnetically conductive and includes a top surface, substantially covering the first plane surface of the permanent magnet, and a bottom surface, substantially covering the second plane surface of the permanent magnet. The cover is at least partially open at the side surfaces of the permanent magnet. Also disclosed is a rotor for an electrical machine, the rotor having permanent magnets fitted into a corresponding module.