All perfect praise be to Allaah , the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
According to the majority of scholars, letting water flow over the feet in the Wudhoo’ without rubbing them is sufficient. Al-Haafith ibn Hajar, may Allaah have mercy upon him, said: "There is a difference in opinion regarding the obligation of rubbing. Contrary to Maalik and Al-Muzni, the majority of scholars do not consider it obligatory."
Commenting on Saheeh Muslim, An-Nawawi, may Allaah have mercy upon him, said:
"The majority of scholars agreed that it is sufficient to make the water flow over the organs to be washed in the Wudhoo’. Rubbing them, however, is not a condition for the validity of the Wudhoo’. On the other hand, Maalik and Al-Muzni stood alone in considering rubbing these parts as a prerequisite."
Notwithstanding, one must make sure that water reaches all the parts that are to be washed.
Allaah Knows best.