The team included 15 players.
Harberts, a senior forward from San Clemente, has averaged 16.2 points and 7.5 rebounds for the Trojans, who are 18-12 and seeded fifth in the Pac-12 tournament that begins Thursday at KeyArena in Seattle.
The Trojans play Arizona (5-24) in a first-round game.
Harberts also was all-conference last season.
Nyingifa, a senior forward from Torrance, also made the all-conference team for the second year in a row. She averaged 19 points and 8.9 rebounds for the eighth-seeded Bruins (13-17), who play Colorado (16-13) in a first-round Pac-12 tournament game.
Fields, a sophomore guard from Montreal, Canada, has averaged 17.3 points.
Stanford senior forward Chiney Ogwumike, who has averaged 27 points and 12.1 rebounds, was voted player of the year for the second year in a row.
Washington’s Kelsey Plum was freshman of the year and Stanford’s Tara VanDerveer coach of the year.