An infusion pump system, comprising: a disposable first portion including a medicament cartridge that includes a barrel which defines a medicament reservoir, medicament in the reservoir, a manifold attached to the barrel, with an inner surface that defines a through-bore having first and second longitudinal ends configured to receive a cannula, an outlet port located between the first and second longitudinal ends of the through-bore that extends from the medicament reservoir and through the inner surface that defines the through-bore, a first part of an occlusion sensor that communicates with the through-bore by way of an aperture so as to expose the first part of the occlusion sensor to the fluid pressure in the through-bore; a cannula that is insertable into the through-bore and has an opening, in fluid communication with the outlet port when the cannula is in position in the through-bore, and first and second seals positioned such that the outlet port and the aperture will be located between the first and the second seals when the cannula is in position in the through-bore, a reusable second portion that includes a motor and a second part of the occlusion sensor and is free of any portion of the medicament fluid path of the infusion pump system; wherein the disposable first portion and the reusable second portion being respectively configured such that the reusable second portion is positionable in an operative position where operation of the motor causes the medicament to be dispensed out of the medicament reservoir and the first and second parts (124, 236) of the occlusion sensor are operative together to detect an occlusion in the medicament fluid path. a disposable first portion including a medicament cartridge that includes a barrel which defines a medicament reservoir, medicament in the reservoir, a manifold attached to the barrel, with an inner surface that defines a through-bore having first and second longitudinal ends configured to receive a cannula, an outlet port located between the first and second longitudinal ends of the through-bore that extends from the medicament reservoir and through the inner surface that defines the through-bore, a first part of an occlusion sensor that communicates with the through-bore by way of an aperture so as to expose the first part of the occlusion sensor to the fluid pressure in the through-bore; a cannula that is insertable into the through-bore and has an opening, in fluid communication with the outlet port when the cannula is in position in the through-bore, and first and second seals positioned such that the outlet port and the aperture will be located between the first and the second seals when the cannula is in position in the through-bore, a medicament cartridge that includes a barrel which defines a medicament reservoir, medicament in the reservoir, a manifold attached to the barrel, with an inner surface that defines a through-bore having first and second longitudinal ends configured to receive a cannula, an outlet port located between the first and second longitudinal ends of the through-bore that extends from the medicament reservoir and through the inner surface that defines the through-bore, a first part of an occlusion sensor that communicates with the through-bore by way of an aperture so as to expose the first part of the occlusion sensor to the fluid pressure in the through-bore; a cannula that is insertable into the through-bore and has an opening, in fluid communication with the outlet port when the cannula is in position in the through-bore, and first and second seals positioned such that the outlet port and the aperture will be located between the first and the second seals when the cannula is in position in the through-bore, a reusable second portion that includes a motor and a second part of the occlusion sensor and is free of any portion of the medicament fluid path of the infusion pump system; wherein the disposable first portion and the reusable second portion being respectively configured such that the reusable second portion is positionable in an operative position where operation of the motor causes the medicament to be dispensed out of the medicament reservoir and the first and second parts (124, 236) of the occlusion sensor are operative together to detect an occlusion in the medicament fluid path.