By DAVID ELLIS/Reported by Sidney Urquhart

Some Bush Administration insiders are acidly recounting the irony of a blunt lecture John Su nunu delivered to former Education Secretary Lauro Cavazos last December. When the chief of staff summoned the ineffectual Cabinet member and asked him to resign, Sununu included a few sharp comments on Cavazos' travel habits. The Secretary usually took along his wife Peggy Ann, and is suspected of paying her fares with frequent-flyer credits he earned on official business--an apparent violation of federal rules requiring those bonuses to be turned over to the government. The couple also preferred to travel on TWA, even when other carriers offered more direct routes. Because Cavazos' son worked for the airline, the Secretary's wife was able to fly free. Sununu's heavy use of military flights earned him a slap on the wrist, but Ca vazos' machinations are the subject of a Justice Department criminal investigation.