A rotary pump comprising: - a body defining a pumping chamber and comprising at least one suction opening (104, 105) and at least one exhaust opening, - a rotor rotatably mounted inside said pumping chamber and having at least one vane, - a first guide provided in the pump body and arranged to guide, in use, a first end of said rotor, - a lid including a second guide having a guiding hole which has certain hole thickness and which is arranged to cooperate, in use, with a second end of said rotor; wherein said lid is made of a metal sheet having a predetermined thickness, and in that it further comprises a cap, which is made of a metal sheet having a thickness smaller than the thickness of said lid and is arranged to seal in fluid-tight manner said guiding hole, the pump being characterized in that said cap is fastened to said lid by means of: - high strength adhesives having sealing power, or - high strength adhesives having sealing power, and interference fit between said cap and said lid, or - braze welding of said cap to said lid, in that said cap comprises a peripheral stepped portion and is fitted on top of a corresponding stepped portion of the lid, said high strength adhesives having sealing power or said braze welding being applied at least onto portions of contact surfaces (x) between said peripheral stepped portion of the cap and said corresponding stepped portion of the lid, and in that said guiding hole of said second guide is arranged to cooperate with said second end of said rotor over its whole hole thickness. - a body defining a pumping chamber and comprising at least one suction opening (104, 105) and at least one exhaust opening, - a rotor rotatably mounted inside said pumping chamber and having at least one vane, - a first guide provided in the pump body and arranged to guide, in use, a first end of said rotor, - a lid including a second guide having a guiding hole which has certain hole thickness and which is arranged to cooperate, in use, with a second end of said rotor; wherein said lid is made of a metal sheet having a predetermined thickness, and in that it further comprises a cap, which is made of a metal sheet having a thickness smaller than the thickness of said lid and is arranged to seal in fluid-tight manner said guiding hole, the pump being characterized in that said cap is fastened to said lid by means of: - high strength adhesives having sealing power, or - high strength adhesives having sealing power, and interference fit between said cap and said lid, or - braze welding of said cap to said lid, in that said cap comprises a peripheral stepped portion and is fitted on top of a corresponding stepped portion of the lid, said high strength adhesives having sealing power or said braze welding being applied at least onto portions of contact surfaces (x) between said peripheral stepped portion of the cap and said corresponding stepped portion of the lid, and in that said guiding hole of said second guide is arranged to cooperate with said second end of said rotor over its whole hole thickness. wherein said lid is made of a metal sheet having a predetermined thickness, and in that it further comprises a cap, which is made of a metal sheet having a thickness smaller than the thickness of said lid and is arranged to seal in fluid-tight manner said guiding hole, the pump being characterized in that said cap is fastened to said lid by means of: - high strength adhesives having sealing power, or - high strength adhesives having sealing power, and interference fit between said cap and said lid, or - braze welding of said cap to said lid, - high strength adhesives having sealing power, or - high strength adhesives having sealing power, and interference fit between said cap and said lid, or - braze welding of said cap to said lid, in that said cap comprises a peripheral stepped portion and is fitted on top of a corresponding stepped portion of the lid, said high strength adhesives having sealing power or said braze welding being applied at least onto portions of contact surfaces (x) between said peripheral stepped portion of the cap and said corresponding stepped portion of the lid, and in that said guiding hole of said second guide is arranged to cooperate with said second end of said rotor over its whole hole thickness.