When Charles Scharf took over at Wells Fargo & Co. last year, tasked with moving the bank past a fake-accounts scandal, he brought in a cleanup crew of former colleagues from his long career on Wall Street.

A new chief operating officer and heads of public affairs, credit cards and strategic planning had all worked with Scharf at JPMorgan Chase & Co. or Bank of New York Mellon Corp. Another longtime JPMorgan executive joined the board. All are white men.