Phosphor bronze or sintered bushes are primarily designed for use in areas where other lubrication methods are difficult.
They come in many forms and are generally impregnated with around 4% lead, some are oil impregnated (a lubricant!) some are even impregnated with carbon pellets to further reduce friction.
However they are not perfect and whilst lubrication is not theoretcally required it will do absolutely no harm whatsoever.
You will notice an increase in the speed of roof movement and also remove some load fro the pump.
Go here https://www.skf.com/group/products/plain-bearings/bushings-thrust-washers-strips/principles/lubrication
Click on the + next to solid bronze bushings and also Sintered bronze bushings for factual info from a manufacturer.
In fact if you open any of the categories they will ALL state that additional lubrication can be advantageous..