A wind turbine generator comprising: a first item having a male portion (102; 202); and a second item having a female portion (111; 211) with an opening; wherein: the first item is a magnet module and the second item is a rotor rim, the magnet module being a unit that comprises a base for housing a plurality of magnets in such a way that the magnets are fixable together to the rotor rim through the base, or the first item is a stator tooth and the second item is a stator housing, the stator tooth being a unit that comprises a base for housing a plurality of coils in such a way that the coils are fixable together to the stator housing through the base; and wherein the shape of the male portion (102; 202) and the shape of the female portion (111; 211) are adapted to each other such that the male portion (102; 202) can be fitted into the opening of the female portion (111; 211); characterized in that the male portion (102; 202) is formed as a stack of sheets comprising a plurality of standard sheets (103; 203) that substantially fits into the opening of the female portion (111; 211) and one or more protruding sheets (104; 204) with dimensions larger than the opening of the female portion (111; 211) such that, in use, the protruding sheets (104; 204) are deformed during insertion of the male portion (102; 202) into the opening of the female portion (111; 211). a first item having a male portion (102; 202); and a second item having a female portion (111; 211) with an opening; wherein: the first item is a magnet module and the second item is a rotor rim, the magnet module being a unit that comprises a base for housing a plurality of magnets in such a way that the magnets are fixable together to the rotor rim through the base, or the first item is a stator tooth and the second item is a stator housing, the stator tooth being a unit that comprises a base for housing a plurality of coils in such a way that the coils are fixable together to the stator housing through the base; and wherein the shape of the male portion (102; 202) and the shape of the female portion (111; 211) are adapted to each other such that the male portion (102; 202) can be fitted into the opening of the female portion (111; 211); characterized in that the male portion (102; 202) is formed as a stack of sheets comprising a plurality of standard sheets (103; 203) that substantially fits into the opening of the female portion (111; 211) and one or more protruding sheets (104; 204) with dimensions larger than the opening of the female portion (111; 211) such that, in use, the protruding sheets (104; 204) are deformed during insertion of the male portion (102; 202) into the opening of the female portion (111; 211). the first item is a magnet module and the second item is a rotor rim, the magnet module being a unit that comprises a base for housing a plurality of magnets in such a way that the magnets are fixable together to the rotor rim through the base, or the first item is a stator tooth and the second item is a stator housing, the stator tooth being a unit that comprises a base for housing a plurality of coils in such a way that the coils are fixable together to the stator housing through the base; and wherein the shape of the male portion (102; 202) and the shape of the female portion (111; 211) are adapted to each other such that the male portion (102; 202) can be fitted into the opening of the female portion (111; 211); characterized in that the male portion (102; 202) is formed as a stack of sheets comprising a plurality of standard sheets (103; 203) that substantially fits into the opening of the female portion (111; 211) and one or more protruding sheets (104; 204) with dimensions larger than the opening of the female portion (111; 211) such that, in use, the protruding sheets (104; 204) are deformed during insertion of the male portion (102; 202) into the opening of the female portion (111; 211).