>think that i have to insert 10 rows into the nested table , it >has to hit the database(server side) 10 times.this will >reduces the performance .
Use a stored procedure or, if number of records is fixed,
in relational manner Iwould do:

select a1 from dual
union all a2 select from dual
...

On the other hand, may be you can build a set (i.e. varray),
convert this set to a table (cast, multicast, table - I really do not find usefull specs. in standard Oracle docs about those) and then try to use "insert select"

For info. look into Oracle cartridges like SDO docs, they have some helpfull examples.