If there is no axial variation, then I suggest using a 2-D crosssecion to solve the problem. In 2-D you can easily draw the large cylinder and smaller heating elements as different circles. You then model the heat generation using internalHeatSource function.
If the problem is indeed 3-D, then you might make a couple of modelling approximation:
- On the blue solid parts create either fully burried heating element as holes. Apply an equivalent heat flux on the inner wall surfaces.
- If heating element is not fully embedded, they also radiate heat to atmosphere, then you can make slots/channels at the location of heating element and apply heat flux BC.