The site is actually for trucks, but it’s the best ABS description I could find.
The way the system works is that on each axle there’s an “exciter ring” that induces a signal to a “pickup” that tells the system the speed of the wheel. When the computer gets a signal from one wheel that indicates that it isn’t turning while the others are, it assumes that tire is slipping and activates the ABS system for that specific wheel.
Since you said you had two hubs corroded to the point of needing replacement it made me wonder what else on those axles may be corroded that may be causing an erroneous signal to the ABS system.