A rotor (106, 200) for an electrical machine comprising: an elongate cylindrical rotor hub; a plurality of permanent magnets arranged in a plurality of rings (204a, 204b, 204c, 204d) around the rotor hub; a rotor sleeve around the permanent magnets adapted to seal the permanent magnets against contact with the fluid in the housing, the rotor sleeve providing primary radial support for retaining the permanent magnets to the rotor hub during operation of the rotor (106, 200) characterized by further including end rings at axially opposing ends of the rotor hub, the inner surface of the end rings abutting the end of the rotor hub and providing axial support to the permanent magnets; wherein the rotor sleeve is constructed from outer and inner fiber-reinforced composite layers including a plurality of fibers and a polymer binder, the fiber being at least one of ceramic, glass, or polymer, or carbon fiber reinforced composite, wherein the outer layers (232, 234) include one or more fiber-reinforced composite layers having a majority of fibers being axially-oriented; and wherein the segmented inner layer (236, 238, 239, 240) beneath the outer layers (232, 234) comprises a plurality of discrete, adjacent, latitudinal non-overlapping, spaced apart circumferential bands (236, 238, 239, 240) of composite material positioned orthogonal to a longitudinal axis of the rotor core assembly, and wherein said circumferential bands (236, 238, 239, 240) being hoop-like layers positioned over, and substantially longitudinally coinciding with the magnet rings (204a, 204b, 204c, 204d); and the fiber-reinforced composite hoop-like layers have primarily circumferentially- oriented fibers; a cylindrical end treatment strip of composite material capable of bonding to the sleeve, wherein a ledge is provided circumferentially on the outside diameter of the end ring, and wherein the ledge serves as a landing platform for the positioning of the end treatment strip, which is wrapped around said end ring's ledge; and on each end ring, a seal sealing between the end ring and the end treatment strip. an elongate cylindrical rotor hub; a plurality of permanent magnets arranged in a plurality of rings (204a, 204b, 204c, 204d) around the rotor hub; a rotor sleeve around the permanent magnets adapted to seal the permanent magnets against contact with the fluid in the housing, the rotor sleeve providing primary radial support for retaining the permanent magnets to the rotor hub during operation of the rotor (106, 200) characterized by further including end rings at axially opposing ends of the rotor hub, the inner surface of the end rings abutting the end of the rotor hub and providing axial support to the permanent magnets; wherein the rotor sleeve is constructed from outer and inner fiber-reinforced composite layers including a plurality of fibers and a polymer binder, the fiber being at least one of ceramic, glass, or polymer, or carbon fiber reinforced composite, wherein the outer layers (232, 234) include one or more fiber-reinforced composite layers having a majority of fibers being axially-oriented; and wherein the segmented inner layer (236, 238, 239, 240) beneath the outer layers (232, 234) comprises a plurality of discrete, adjacent, latitudinal non-overlapping, spaced apart circumferential bands (236, 238, 239, 240) of composite material positioned orthogonal to a longitudinal axis of the rotor core assembly, and wherein said circumferential bands (236, 238, 239, 240) being hoop-like layers positioned over, and substantially longitudinally coinciding with the magnet rings (204a, 204b, 204c, 204d); and the fiber-reinforced composite hoop-like layers have primarily circumferentially- oriented fibers; a cylindrical end treatment strip of composite material capable of bonding to the sleeve, wherein a ledge is provided circumferentially on the outside diameter of the end ring, and wherein the ledge serves as a landing platform for the positioning of the end treatment strip, which is wrapped around said end ring's ledge; and on each end ring, a seal sealing between the end ring and the end treatment strip.