ELIZABETH, N.J. -- Wakefern Food Corp. here had sales of $3.73 billion in 1993, ended Sept. 30. This represents an increase of 3.6% from the $3.6 billion reported in 1992, executives told shareholders at the annual meeting here. Wakefern, a member-owned cooperative, supplies 180 ShopRite stores, most of which are independently owned, in New Jersey, New York, Pennsylvania, Connecticut and Delaware. "By continuing to offer ShopRite customers excellent value and prices, we have maintained our position as the leader in our marketplace," said Thomas F. Infusino, chairman and chief executive. Jerome Yaguda, president, said Wakefern members have opened 10 new stores so far this year.