A device for use in a subterranean well can include a component which degrades in the well, the component being at least one of the group comprising: a) an electrical element which conducts electricity in the well, b) a magnetic element which produces a magnetic field in the well, and c) a substrate which structurally supports an electrical circuit. A method of constructing a device for use in a subterranean well can include determining an environmental condition to be experienced by a component of the device in the well, the component being at least one of the group comprising: a) an electrical element which conducts electricity in the well, b) a magnetic element which produces a magnetic field in the well, and c) a substrate which supports an electrical circuit; selecting the component which degrades when exposed to the environmental condition; and incorporating the component into the device.