Maryland's eight incumbent members of Congress found little to be concerned about in the way of challengers as the deadline for entry in the May 8 Maryland primary passed at 9 p.m. Monday.

Though all the incumbents have competition in the primary, and all but one will face opposition in the general election, the group of challengers is composed mostly of perennial candidates and political unknowns.

Republican State Party Chairman Allan C. Levey held a news conference here Monday, asserting that the GOP lineup was "as good as any we've had."

He pointed to the candidacy of Jayne H. Plank, a former mayor of Kensington, who stepped down from her State Department job to seek the GOP nomination to face Rep. Michael D. Barnes (D-Md.) in the 8th Congressional District in Montgomery County. But other GOP officials conceded that Plank likely will be "a sacrificial lamb" to the popular Barnes in November.

Barnes faces only token opposition in the primary, as does Rep. Steny H. Hoyer, the Democratic incumbent from the 5th Congressional District, which includes Prince George's County.

The most exciting Republican primary is likely to be in the 2nd Congressional District, where Rep. Clarence D. Long (D-Md.) has represented voters for two decades. The GOP's Helen Delich Bentley has given Long competition in the past in the district, which includes Baltimore and Harford counties.

Now she has competition in her own party from David Smick, a former aide to U.S. Rep. Jack Kemp (R-N.Y.). Indeed, their rivalry became so heated that Levey got them to sign a sort of peace pact recently to avoid bitterness that could hurt GOP chances in the general election.

In the 8th Congressional District, Rep. Beverly Byron (D-Md.) is likely to have some colorful competition in the general election, no matter which candidate wins the Republican primary. Melvin R. Perkins, a perennial candidate from Baltimore whose previous nomination by default was repudiated by local GOP officials, is running again. His competition is Robin Ficker of Potomac, a former state legislator whose gadfly politics and long speeches often emptied the House chamber in Annapolis.

Along with the congressional races, the primary includes contests for judgeships and for delegates to the Republican and Democratic national conventions.

If candidates other than Walter F. Mondale are politically alive by May 8, that contest is likely to be a spirited one. Forty-two delegates to the Democratic convention in San Francisco will be chosen from among candidates fielded by each presidential candidate in the primary. Several of the candidates are fielding full slates on what will be a long and confusing ballot.

On the Republican side, several interesting names showed up among candidates vying for 24 seats assigned to Maryland at the GOP national convention in Dallas. Former congressman Newton I. Steers is running for a seat from the 8th Congressional District. The GOP delegate races also include the offspring of two well-known Maryland Republicans. Larry Hogan Jr., the son of former Prince George's County Executive Larry Hogan, is running, as well as former U.S. representative Robert Bauman's daughter, Eugenie Marie Bauman.

Here is a list of Washington-area candidates who have filed for Congress for the May primary election:

4th District:

Democrats: John L. Ball, Riverdale; Edward Barnum, Glen Burnie; Howard M. Greenebaum, Arnold; Irene E. Riley, Severna Park.

Republican: Marjorie S. Holt (incumbent), Severna Park.

5th District:

Democrats: Steny H. Hoyer (incumbent), Berkshire; Lawrence E. Keval, Bowie; Craig E. Ransom, Laurel.

Republicans: John E. Ritchie, Laurel; Kenneth M. Robinson, Fort Washington; John E. Sellner, Fort Washington.

6th District

Democrats: Beverly B. Byron (incumbent), Frederick; John P. Donoghue, Williamsport; William B. McMahon, Williamsport.

Republicans: Robin Ficker, Potomac; Melvin Perkins, Baltimore.

8th District

Democrats: Michael D. Barnes (incumbent), Kensington; Thomas A. Torchia, Rockville.

Republicans: Wallace D. Barlow, Bethesda; Donald J. Chaney, Ashton; Albert Ceccone, Chevy Chase; Michael P. D'Aiuto, Wheaton; Jayne H. Plank, Kensington.